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SA academic patents acid mine water treatment

Sep 13 2013 14:29

Wastewater is treated at the Macassar Treatment Plant outside Cape Town. (Duncan Alfreds, News24)

Johannesburg - Rand Water chairperson in water utilisation Professor Jannie Maree has received a United States patent for an acid mine water treatment process.

The magnesium-barium-hydroxide (MBO) process, which removes metals and sulphate from mine water, offered South Africa a technically sound and cost-effective solution for the acid mine water problem, Maree said in a statement.

"In recent years, numerous mines have closed down or are in the process of being decommissioned.

"It was found that the patented process can solve the acid mine water problem and generate income at the same time," he said.

The problem could be solved via economic principles instead of through government intervention by means of policies and legislated control measures.

Maree said removing metals and sulphate with the MBO process could produce water that contained levels low enough to be acceptable as drinking water. This was provided the levels of sodium and chloride in the treated water was low.

He said the patented process was used with great success at laboratory level.

Water from coal and gold mines was used. This was described in the master's dissertation of a Tshwane University of Technology (TUT) postgraduate student Hangwi Bologo.

"In this process magnesium hydroxide (Mg(OH)2) is used for the neutralisation and removal of metals while barium hydroxide (Ba(OH)2) is used for the removal of sulphate in the water, as well as magnesium ion (Mg2+) that was added as magnesium hydroxide (Mg(OH)2)," he said.

The MBO process also made provision for the use of ammonium hydroxide for neutralisation and metal removal in the place of magnesium hydroxide. This was described in the master's dissertation of another postgraduate student, Mavis Maila.

Maree said there were a number of benefits of the MBO process.

Less sludge was produced when magnesium hydroxide was used for neutralisation, instead of calcium hydroxide.

This was because of the high solubility of magnesium sulphate compared to calcium sulphate, he said.

Another benefit was that the mixed product of barium sulphate and magnesium hydroxide could be separated with carbon dioxide.

There was also lower alkali cost, since both the cation barium (Ba2+) and the cation hydroxide (OH-) were utilised.

The Ba2+ was used for the removal of sulphate (SO42-) and OH- for the removal of the Mg2+.

Maree said the patented process would be ready for full-scale implementation as soon as the thermal studies on the processing of BaSO4 to Ba(OH)2 had been completed by postgraduate students.

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patents  |  mines  |  acid mine water



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